期刊
JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE
卷 119, 期 2, 页码 333-348出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/2013JF002842
关键词
ice stream; glacial seismology; grounding line
资金
- UNAVCO instrument center
- PASSCAL instrument center
- U.S. National Science Foundation Office of Polar Programs [ANT-0944671, ANT-0944794]
- Directorate For Geosciences
- Office of Polar Programs (OPP) [0944286] Funding Source: National Science Foundation
- Directorate For Geosciences
- Office of Polar Programs (OPP) [0944794] Funding Source: National Science Foundation
The tidally modulated, stick-slip events of Whillans Ice Stream in West Antarctica produce seismic energy from three locations near the grounding line. Using ice velocity records obtained by combining time series from colocated broadband seismometers and GPS receivers installed on the ice stream during the 2010-2011 and 2011-2012 austral summers, along with far-field seismic recordings of elastic waves, we locate regions of high rupture velocity and stress drop. These regions, which are analogous to asperities in traditional seismic fault studies, are areas of elevated friction at the base of the ice stream. Slip events consistently initiate at one of two locations: near the center of the ice stream, where events associated with the Ross Sea high tide originate, or a grounding-line spot, where events associated with the Ross Sea low tide initiate, as well as occasional high-tide events following a skipped low-tide event. The grounding-line site, but not the central site, produces Rayleigh waves observable up to 1000km away, through fast expansion of the slip area. Grounding-line initiation events also show strong directivity in the downstream direction, indicating initial rupture propagation at 1.5km/s, compared to an average of 0.150km/s for the entire slip event. Following slip initiation, additional seismic energy is produced from two sources located near the grounding line: first at the downstream end of Subglacial Lake Engelhardt and second toward the farthest downstream extent of the ice stream. This evidence suggests that the stronger, higher-friction material along the grounding line controls motion throughout the stick-slip region. Key Points Ice stream seismic and GPS observations show grounding line control of motion GPS and seismic signals are combined, producing a high fidelity time series Teleseismic phases are radiated by ice stream sticky spots
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据